Comparison of the usefulness of plasma levels of oxidatively modified forms of albumin in estimating kidney dysfunction in diabetic patients

Abstract

Purpose: Advanced oxidation protein products (AOPP) and ischemia-modified albumin (IMA) are forms of oxidatidatively modified albumin and have recently been investigated as indicators of oxidative stress. They are increased in different disorders, including diabetes mellitus, as a result of hyperglycaemia, oxidative stress and hypoxia. The usefulness of the plasma levels of these two parameters in estimating kidney dysfunction in type 2 diabetic patients (T2DM) was compared in this study. Methods: Plasma levels of AOPP and IMA were determined spectrophotometrically in 218 individuals, 153 patients with T2DM and 65 healthy people.. The urinary albumin/creatinine ratio (UACR) was used as the reference to define the stage of kidney dysfunction by the assessment of the degree of albuminuria. Results: Receiver Operating Characteristic (ROC) curve analysis, likelihood ratio (LR), and Youden’s index (J) revealed that AOPP and IMA had acceptable sensitivities and specificities in individuals with different degrees of albuminuria; however, AOPP had higher values of the area under the curve (AUC: 0.934) than IMA, as well as 100% sensitivity and 77.01% specificity for distinguishing patients with micro- and macroalbuminuria. Conclusions: Both AOPP and IMA may be helpful clinical markers for estimating kidney dysfunction, but AOPP is better able to identify diabetic patients with nephropathy. We suggest that AOPP is almost ideal for discriminating between T2DM patients with micro- and macroalbuminuria.